Tanning.



7 Ho Drawing.

erases Parana enrich,

.eLrnon'sE SEYEWETZ AND Louis MEUNIER, or LYON, FRANCE.

TANNING.

To all: whom it may concern:

Be it known that We, ALPHoNsn Snrnwn'rz and Louis Mailman, citizens of the French Republic, residing at Lyon, in France, have invented certain new and useful Improve ments in Tanning, of which the following 1s a specification.

The Jresentinvention is based u on the following observations:-1. If a skin is tanned with gallo-tannic acid or tannin produeed from the gall-nut, in the absence ofalkaii and oxygen, the product obtained has the appearance of leather, very slightly colored, but is gelatinized by the action of hot.

C0211 OH i -gen CO2 OH Call" and since unoxidized phenols of this character do not tan while oxidized oroXidiZing phenols do tan, it appears that the tanning action is more particularly due to the oxidation 01 these phenolic groups. Wehave also found that other phenolic compounds and in particular those derived from the benzenoid hydrocarbons used under conditions favorable to their oxidation are capable of converting skin into true leather. This result can be obtained, in a greater or less degree, with a large number of simple and complex phenols, and also with their substitutive derivatives.

Of the compounds which give the best Specification of Letters Patent.

Application filed January 29, 1908. Serial No. 413,272.

Patented as. as, item.

results the following may be cited :-hydrokinone on cmubon so u.

Proceeding from these observations, and more particularly from that which indicates that the phenols must be oxidized in order to combine with the dermal substance, We also investigated the question as to Whether the products of direct oxidation of these phenols, that is products formed by an oxidation insullicient to destroy the cyclic strucso ture of the phenol, more particularly the kinones and their derivatives, are capable of directly combining with dermal fiber to convert the same into leather Without the co-action of free oxygen. lVith regard to these products of oxidation of the benzenoid hydrocarbons it has been found that. ordinary kinone OGII4 O (4) p and its homologues, such as l()ll1l(l11()ll0 orn -o 1 both of which may be regarded as oxida tion products oi phenols, yield very remarkable results and are capable, even when used great strength and suppleness, and constitute in fact true leather.

The kinones derived from the products of substitution of hydrokinone, for example the derivative obtained by the oxidation of chlorhydrokinone ofiaaoia 4 (the adurol of commerce), behave in the same way as ordinarykinone. Kinone chlorimid NCl on also has the same tanning properties as klnone. The lnterinediate oxids, between the kinones and phenols, such as quinhydrone on ean are also capable of converting dermal matter lnto leather.

The tanning action is specifically difierent with the various phenolic materials employed. Where these bodies oxidize rapidly, as in the case of hydrokinone, the action is rapid; where they oxidize with greater difliculty, as in the case of resorcin, the action is slower. The tanning action being dependent upon the presence of the oxidized bodies, obviously it is quicker where the aqueous tanning solution is made of preformed oxidation products than when oxidation and tanning go on simultaneously; and particularly with dilticultly oxidizable phenols. The tanning power of these oxidation products is remarkable. The kinones and kinhydrones or quinhydrones, derived from the direct oxidation of phenols carry; ingtwo OH groups in the ortho or para position, and particularly the latter, when dissolved in water rapidly transform hide into imputrescible leather resisting the action of boiling water. One part of ordinary kinone or quinone, for example, sul'lices to tan- 100 parts of hide, producing an insolu-. bility which can only be realized by at least 35 to 40 parts of any of the ordinary tannins. a

The presentmethod oi. tanning can of course be employed in conjunction with ordinary tanning methods.

Examples will now be given, firstly of the use of kinones and their substitution products and kinone chlorimid, and secondly oi the use of phenols.

Example 1. Direct twining with Im'nones, substitution products and Malone chZ0rimid-As an example may be taken ordinary kinone applied to the tanning of calf-skin. For 100 kilos of soft, untanned skin, approximately 400 grams ofkinone are dissolved in 100 liters of water and gradually added, at intervals, to the skin placed in a vat having an agitator, or preferably in a rocking or turning drum. It will be found that the tanning proceeds with'remarkable regularity and with a drum turning say 10 revolutions per minute the tanning may be completed in 5 hours. lVith sheepskins, incisions show the tanning to be complete throughout. The skin first acquires a pink tint, and then successively violet and brown colors. At the same time it swells appreciably. Agitation assists the propagation. of the tanning action in the interior of the skin. The length of-tinie required is considerably shorter in the case of kinone than in the case of hydrokinone in alkaline liquor and in contact with air (Example II). Approximately three days are required if the agitation only takes place at intervals, but the period may be modified by modifying the concentration of the kinone liquor. After the tanning the skin is dyed, dressed and finished as in the case of chrome leather, according to the particular purpose for which it is required. Sheep-skins may be treated in the same manner; Taking 100 kilograms of sheep-skin freed of wool, rinsed and dried, the material may be introduced into a rotating drum provided with a hollow shaft and the .kinone solution introduced through this shaft in such quantity as to. represent about 400 grams of kinone. This amount of material may be dissolved in 100 liters of water. he made gradually and in small portions while the latter maybe added more rapidly. While kinone is soluble in water only'to the extent of about half a per cent., this solubility is amply sutilcient for the present purposes.

Example I I Tanning with phenol derivaii ves.As an example may be taken hydrokinone applied to the tanning of sheepfls skin in the presence of alkaliandin contact with air. For 100. kilograms of skin 350 grams of hydrokinone are dissolved'in wa ter with 500 grams of crystallized carbonate of soda. The skin is placed in' a vat having an agitating device to aid i: aeration and oxidation, and is covered with water. The alkaline solution of hydrokinone The first additions are to is gradually added, with energetic stirring, v

and. is allowed to act until the skin has acsemen methods described it is not necessary to previously mordant the same with sumach, as in the case of chrome leather, since the skin has great affinity for the coloring matter.

Skins already tanned with chrome can even be successfully mordanted by means of kinone or its derivatives, with results comparable to those obtained with sumach. in tanning with preformed oxidation products of phenols, such as kinhydrone or quinhydrone, the operation is conducted. exactly as previously described in the case of ordinary lrinone, except that the lrinhydrone may be used in the form of a powder in a bag attached to the manhole or other convenient portion of the interior of the rotating drum,

kinhydrone being only slightly soluble in water. And, as in the case of kinone, the

proportions of kinhydrone required will vary according to the use to be made of the leather. About 300 to 800 grams are used, this depending upon the leather to be made. It may be noted in this connection that l in hydrone when dissolved in water behaves for the'present purposes as if it were a mix ture of the solutions of kinone and hydrokinone.

The oxidation products of the substitutive --phenols, such as the sult'onated derivatives,

may be employed. Salts otthese deriva tives may also be used. For instance, ben- Zokinone snlfonic acid is useful and may be employed as a shdium salt. It is very solublc in. water, possesses no odor and does not exercise any irritating action. It has to be used in somewhat greater proportions than ordinary kinone, as, for instance, from 600 to 1,000 grains per 100 kilograms of hide. Using this substance the skin takes a red color a different from the violet color given at one Istate of the tanning with ordinary kinone. This substance is to be added very slowly as it is rapidly fixed by the hide. ihe addition with sheep-skin may last over a period of T to 8 hours. It should not be employed in a bag in a solid state. Sul'fonatcd hydro.

kinone may housed in an advantageous way, by dissolving in an alkaline solution and permitting free contact with air; About SOOgrams of the sult'onated hydrokinone suilice for 100 kilograms of hide. The details of operation are as before. tans very well but the color after tanning is somewhat redder and less violet than is the case in using the non-sulfonated hydrokinone.

Using these new tanning agents it is found that in general vat tanning is better for leathers requiring a certain degree of suppleness, such as strap and harness leather, etc. Suspension tanning is better for leathers requiring a certain firmness, such as sole leather.

The exact proportion of the new agents to be used will depend upon the use to be made of the leather. The greater the resistance which it is to offer to waterthe greater the amount-of the tanning agent which must be employed. If a subsequent tanning with another substance is to be used, the proportions are of course reduced somewhat. In the case of sole and strap leathers double tanning is 'ot'ten'advantageous, for instance tanning first w ith kinone and then with tannin, since it permits diminishing very considerably the length of time required for tanning as compared with the time required where only vegetable tanning materials are employed. The leather so produced is also heavier since the kinone has the property of permitting a remarkable increase in the amount of the vegetable extract absorbed in the later operation. The increase in amount of leather produced may be from five to ten per cent. Leathers with these mixed tannings resist the action of water very well.

Leather prepared by the process set forth has the following characteristics.

The hide 1. Great thoroughness of tanning, giving it great power of resisting the action of Water, even boiling water, notwithstanding the small proportion of tanning matter used. 2. Great softness to the touch, shceps leather being rendered almost as soft as chaxnois leather. Great durability. 4t. Great afiinity for coloring matter, which obviates the use of sumach, injurious to the grain of the leather.

What we claim as our invention and desire to secure by Letters Patent '0? the United States is l. The process of. tanning which coinprises treating hide with oxidation products of a phenol, said products having a. cyclic structure.

2. The process of tanning which comprises treating hidc with oxidation products of a phenol, said products having a cyclic structure, while simultaneously producing said oxidation products.

of a phenol, said products comprising a kin- In witness whereof We have signed this one. specification in the presence of two witnesses, 4. The process of tanning which com- ALPHON SE SEYEWETZ. prises treatingjiidc with oxidation products LOUIS MEUNIER. 5 of a phenol, said products comprising a sub \Vitnesses: v stance of the kinone type and having a cyclic GASTON JEANNIAUX,

structure. 1 THos. N. BROWNE. 

